Many microelectronic devices have bump bond structures with copper pillars and solder bumps on the copper pillars, to provide connections to lead frames and other package terminals. Increasing demand for miniaturization of the copper pillars and higher pillar densities has increased the current density through the copper pillars and the solder bumps. Electromigration failure in bump bond structures with solder directly contacting the copper pillars has been attributed to the depletion of intermetallic compounds at the interface of the copper and the solder, which usually contains tin. These failures have led to use of barrier layers between the copper and the solder. Nickel, nickel phosphorus, nickel phosphorus tungsten, nickel iron phosphorus, nickel rhenium phosphorus, cobalt phosphorus, and cobalt tungsten phosphorus, have been reported as potential candidates for the barrier layers. Each of these layers suffer from disadvantages. Nickel forms a brittle intermetallic compound of Ni3Sn4 which can pose reliability issues. Even though a thin nickel layer on copper can reduce the interfacial reactions with tin-rich solders at a low reflow temperature, it may not be so effective when a reflow process is performed at a higher temperature and for a longer period. The remaining proposed barrier layer compositions react with tin-rich solder, leading to formation of brittle intermetallic compounds, resulting in fractures or voids in the bump bond structure.